The present invention relates to a system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices.
Gas-lift wells have been in use since the 1800""s and have proven particularly useful in increasing efficient rates of oil production where the reservoir natural lift is insufficient (see Brown, Connolizo and Robertson, West Texas Oil Lifting Short Course and H. W. Winkler, Misunderstood or Overlooked Gas-lift Design and Equipment Considerations, SPE, p. 351 (1994)). Typically, in a gas-lift oil well, natural gas produced in the oil field is compressed and injected in an annular space between the casing and tubing and is directed from the casing into the tubing to provide a xe2x80x9cliftxe2x80x9d to the tubing fluid column for production of oil out of the tubing. Although the tubing can be used for the injection of the lift-gas and the annular space used to produce the oil, this is rare in practice. Initially, the gas-lift wells simply injected the gas at the bottom of the tubing, but with deep wells this requires excessively high kick off pressures. Later, methods were devised to inject the gas into the tubing at various depths in the wells to avoid some of the problems associated with high kick off pressures (see U.S. Pat. No. 5,267,469).
The most common type of gas-lift well uses mechanical, bellows-type gas-lift valves attached to the tubing to regulate the flow of gas from the annular space into the tubing string (see U.S. Pat. Nos. 5,782,261 and 5,425,425). In a typical bellows-type gas-lift valve, the bellows is preset or pre-charged to a certain pressure such that the valve permits communication of gas out of the annular space and into the tubing at the pre-charged pressure. The pressure charge of each valve is selected by a well engineer depending upon the position of the valve in the well, the pressure head, the physical conditions of the well downhole, and a variety of other factors, some of which are assumed or unknown, or will change over the production life of the well.
Several problems are common with bellows-type gas-lift valves. First, the bellows often loses its pre-charge, causing the valve to fail in the closed position or changing its setpoint to operate at other than the design goal, and exposure to overpressure causes similar problems. Another common failure is erosion around valve seat 319 and deterioration of the ball stem in the valve. This leads to partial failure of the valve or at least inefficient production. Because the gas flow through a gas-lift valve is often not continuous at a steady state, but rather exhibits a certain amount of hammer and chatter as ball 318 rapidly opens and closes, ball and valve seat degradation are common, leading to valve leakage. Failure or inefficient operation of bellows-type valves leads to corresponding inefficiencies in operation of a typical gas-lift well. In fact, it is estimated that well production is at least 5-15% less than optimum because of valve failure or operational inefficiencies. Fundamentally these difficulties are caused by the present inability to monitor, control, or prevent instabilities, since the valve characteristics are set at design time, and even without failure they cannot be easily changed after the valve is installed in the well.
It would, therefore, be a significant advance if a system and method were devised which overcame the inefficiency of conventional bellows-type gas-lift valves. Several methods have been devised to place controllable valves downhole on the tubing string but all such known devices typically use an electrical cable along the tubing string to power and communicate with the gas-lift valves. It is often highly undesirable and in practice difficult to use a cable along the tubing string either integral with the tubing string or spaced in the annulus between the tubing and the casing because of the number of failure mechanisms present in such a system. Other methods of communicating within a borehole are described in U.S. Pat. Nos. 5,493,288; 5,576,703; 5,574,374; 5,467,083; 5,130,706.
U.S. Pat. No. 6,070,608 describes a surface controlled gas lift valve for use in oil wells. Methods of actuating the valve include electro-hydraulic, hydraulic, and pneumo-hydraulic. Sensors relay the position of the variable orifice and critical fluid pressures to a panel on the surface. However, when describing how electricity is provided to the downhole sensors and valves, the means of getting the electric power/signal to the valves/sensors is described as an electrical conduit that connects between the valve/sensor downhole and a control panel at the surface. U.S. Pat. No. 6,070,608 does not specifically describe or show the current path from the device downhole to the surface. The electrical conduit is shown in the figures as a standard electrical conduit, i.e., an extended pipe with individual wires protected therein, such that the pipe provides physical protection and the wires therein provide the current path. But such standard electrical conduits can be difficult to route at great depths, around turns for deviated wells, along multiple branches for a well having multiple lateral branches, and/or in parallel with coil production tubing. Hence, there is a need for a system and method of providing power and communications signals to downhole devices without the need for a separate electrical conduit filled with wires and strung along side of production tubing.
U.S. Pat. No. 4,839,644 describes a method and system for wireless two-way communications in a cased borehole having a tubing string. However, this system describes a downhole toroid antenna for coupling electromagnetic energy in a waveguide TEM mode using the annulus between the casing and the tubing. This toroid antenna uses an electromagnetic wave coupling that requires a substantially nonconductive fluid (such as refined, heavy oil) in the annulus between the casing and the tubing as a transmission medium, as well as a toroidal cavity and wellhead insulators. Therefore, the method and system described in U.S. Pat. No. 4,839,644 is expensive, has problems with brine leakage into the casing, and is difficult to use for downhole two-way communication. Thus, a need exists for a better system and method of providing power and communications signals to downhole devices without the need for a nonconductive fluid to be present in the annulus between the casing and tubing.
Other downhole communication concepts, such as mud pulse telemetry (U.S. Pat. Nos. 4,648,471 and 5,887,657), have shown successful communication at low data rates but are of limited usefulness as a communication scheme where high data rates are required or it is undesirable to have complex, mud pulse telemetry equipment downhole. Still other downhole communication methods have been attempted, see U.S. Pat. Nos. 5,467,083; 4,739,325; 4,578,675; 5,883,516; and 4,468,665. Hence, there is a need for a system and method of providing power and communications signals to downhole devices at higher data rates and with available power to operate a downhole device.
It would, therefore, be a significant advance in the operation of petroleum wells if tubing, casing, liners, and/or other conductors installed in wells could be used for the communication and power conductors to control and operate devices and sensors downhole in a petroleum well.
Still other downhole permanent sensors and control systems have been attempted. See U.S. Pat. Nos. 5,730,219; 5,662,165; 4,972,704; 5,941,307; 5,934,371; 5,278,758; 5,134,285; 5,001,675; 5,730,219; and 5,662,165. It is desirable in many types of petroleum wells to be able to sense downhole conditions and to control conditions downhole. Surface indications of production conditions are useful, but feedback to determine optimum production of the well can take many hours and even days. Particularly in multilateral completions, it is desirable to sense operating conditions in each lateral and to be able to control the conditions in each lateral.
It would, therefore, be a significant advance in the operation of petroleum wells in general and gas-lift wells in particular, if sensors for determining flow characteristics in the well could work with controllable valves and surface controls to optimize operating parameters in a well. Generally, it would be a significant advance to provide for redundant communication and control capability to overcome noisy or lossy conditions in the well and provide for failure of individual communication devices. All references cited herein are incorporated by reference to the maximum extent allowable by law. To the extent a reference may not be fully incorporated herein, it is incorporated by reference for background purposes, and indicative of the knowledge of one of ordinary skill in the art.
The problems and needs outlined above are largely solved and met by the present invention. Accordingly, a system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices are provided.
In accordance with one aspect of the present invention, a communication system is provided. The communications system comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first and second communication devices are each electrically connected to the electrically conductive portion of the piping structure along the first location and second location, respectively, and each is adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the first communication device and the electrical connection location for the second communication device, and such that the first communication device can communicate with the second communication device via the piping structure.
In accordance with another aspect of the present invention, a system for providing communications among devices in a well is provided. The system comprises a piping structure, a master communication device, a plurality of slave communication devices, and an induction choke. The piping structure is within the well and the piping structure has an electrically conductive portion. The master communication device is electrically connected to the electrically conductive portion of the piping structure, and the master communication device is adapted to send and receive communication signals via time-varying current. The plurality of slave communication devices is electrically connected to the electrically conductive portion of the piping structure, and the slave communication devices are adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the master communication device and the electrical connection locations for the slave communication devices, and such that the master communication device can communicate with the slave communication devices via the piping structure. Also, at least two of the slave communication devices can communicate with each other via the piping structure.
In accordance with yet another aspect of the present invention, a communications system is provided. The communications system comprises a piping structure, a first communication device, an induction choke, an electrical current transformer, and a second communication device. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first communication device is electrically connected to the electrically conductive portion of the piping structure along the first location, and the first communication device is adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the first communication device and an electrical return. The electrical current transformer is located about part of the electrically conductive portion of the piping structure along the second location. The transformer is located along the piping structure between the electrical connection location for the first communication device and the induction choke, and the transformer is adapted to transform current flowing within the piping structure to an induced secondary current in the transformer. The second communication device is electrically connected to the transformer, such that the second communication device can communicate with the first communication device via the transformer and the piping structure.
In accordance with still another aspect of the present invention, a communication system for a petroleum well is provided. The communications system comprises a piping structure, a computer system, a downhole device, and an unpowered ferromagnetic induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The piping structure is part of a petroleum production system for the petroleum well. The computer system is electrically connected to the electrically conductive portion of the piping structure along the first location. The computer system comprises a source of time-varying current and a first communication device. The first communication device is adapted to send and receive spread spectrum communication signals along the electrically conductive portion of the piping structure via time-varying current waveforms. The downhole device is electrically connected to the electrically conductive portion of the piping structure along the second location. The downhole device comprises a second communication device. The second communication device is also adapted to send and receive spread spectrum communication signals along the electrically conductive portion of the piping structure via time-varying current waveforms. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the choke is adapted to route time-varying current flowing within the electrically conductive portion of the piping structure between the computer system and the downhole device, and such that the first communication device can communicate with the second communication device via the electrically conductive portion of the piping structure. The downhole device can comprise a sensor that is adapted to take measurements and generate sensor data, and the computer system can be adapted to process the sensor data received from the first communication device via the second communication device.
In accordance with yet another aspect of the present invention, a petroleum well for producing petroleum products (e.g., oil, natural gas) is provided. The petroleum well comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure is part of the petroleum well system (e.g., production tubing and/or well casing). The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first communication device is electrically connected to the electrically conductive portion of the piping structure along the first location. The first communication device is adapted to send and receive communication signals via time-varying current. The second communication device is electrically connected to the electrically conductive portion of the piping structure along the second location. The second communication device is adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure. The induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the first communication device and the electrical connection location for the second communication device, such that the first communication device can communicate with the second communication device via the piping structure. The induction choke can comprise a ferromagnetic material, and it can be unpowered. The oil well may also comprise a controllable valve, where the controllable valve is electrically connected to the second communication device such that the valve can be remotely controlled via the second communication device.
In accordance with a further aspect of the present invention, a method of communicating with a remote device is provided. The method comprises the steps of providing an induction choke about a portion of a piping structure; generating a communication signal with a first communication device; transmitting the signal via a time-varying current along the piping structure using the first communication device; routing the time-varying current within the piping structure using the induction choke; and receiving the signal in the remote device via the time-varying current traveling within the piping structure. In the method, the communication signal can be a spread spectrum signal.
In accordance with another aspect of the present invention, a method of communicating with a downhole communication device in a well. The method comprises the steps of providing an induction choke about a portion of a piping structure in the well; generating a spread spectrum signal with a surface communication device; transmitting the signal via a time-varying current along the piping structure using the surface communication device; routing the time-varying current within the piping structure using the induction choke; and receiving the signal in the downhole communication device via the time-varying current traveling within the piping structure. The method may further comprise the steps of receiving the signal with a relay communication device located along the piping structure between the surface communication device and the downhole communication device; amplifying the signal with the relay communication device; and transmitting the signal along the piping structure using the relay communication device. Also, the method may further comprise the steps of generating another spread spectrum signal with the downhole communication device; transmitting the another signal via another time-varying current along the piping structure using the downhole communication device; routing the another time-varying current within the piping structure using the induction choke; and receiving the signal in the surface communication device via the piping structure.